From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E69BB1CA6AF for ; Tue, 3 Sep 2024 13:24:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725369860; cv=none; b=fMwGCDYgejKA3Ex2jjU/IsMj5wzGeNJy6ZWCGxpU5mhfltxHfJgq0Ex2P2SeUPqa4dDUnMOKWqyKN1RxVqgSBC0M+2CWaWCQcpDO0y7OP5iwC5GW+VYOwDRBDOAaEP5vKuNzl3XbRPFs8g6/YWsTsoBnorpsL3tDMwCb6vxNEOQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725369860; c=relaxed/simple; bh=8YVLXhDhqqmJ8iift7tYrNvCIwI3ZUn4scQZalvinuE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FuxnHFIwbl0Q6dXcJsNSD1IYWkJoiYoSrOQ75ikHc4pBYRRaJsjqrJ5p0HutXv0psD6W8JpZAD4gai1QkIAvkvrkx5JpaImQbeukL8eIaP1yCfg3pYdldxyBuq5nTDyQYXOh8gER9zGFqtw3Lq9LvCJ1koosOK33vUkYm9Ds03Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=PzwIGbkm; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PzwIGbkm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1725369857; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ghPHEvdoDmipgIdCSuvU6E6B9zqjyhhmpEJwlzNWqhQ=; b=PzwIGbkm89P+HoJNtn74Knbeu97ulaLLvl6iuF1nTTpJL8ZpS9SarFTD/jG8REvCeoVSa5 Z+RYPKP8OnigG6DodAjBhEPpP+E96opsasoPkk0TJqu2V+xkTXoqFq92jEXZOaucusHyWG tHCgX2eRLZeXziRDkFhIKVKFYPxNKJQ= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-682-no3ofb49PoWW46HWr9IHKA-1; Tue, 03 Sep 2024 09:24:14 -0400 X-MC-Unique: no3ofb49PoWW46HWr9IHKA-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4293818EA80D; Tue, 3 Sep 2024 13:24:12 +0000 (UTC) Received: from [10.2.16.89] (unknown [10.2.16.89]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4E82C19560AE; Tue, 3 Sep 2024 13:24:09 +0000 (UTC) Message-ID: <7fa3dbd5-7c2e-4614-a5f4-258546cb090b@redhat.com> Date: Tue, 3 Sep 2024 09:24:08 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] sched/isolation: Add HK_FLAG_SCHED to nohz_full To: Frederic Weisbecker Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org References: <20240818234520.90186-1-longman@redhat.com> <20240818234520.90186-2-longman@redhat.com> Content-Language: en-US From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On 9/3/24 09:10, Frederic Weisbecker wrote: > Le Sun, Aug 18, 2024 at 07:45:18PM -0400, Waiman Long a écrit : >> The HK_FLAG_SCHED/HK_TYPE_SCHED flag is defined and is also used >> in kernel/sched/fair.c since commit de201559df87 ("sched/isolation: >> Introduce housekeeping flags"). However, the corresponding cpumask isn't >> currently updated anywhere. So the mask is always cpu_possible_mask. >> >> Add it in nohz_full setup so that nohz_full CPUs will now be removed >> from HK_TYPE_SCHED cpumask. >> >> Signed-off-by: Waiman Long >> --- >> kernel/sched/isolation.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c >> index 5891e715f00d..a514994af319 100644 >> --- a/kernel/sched/isolation.c >> +++ b/kernel/sched/isolation.c >> @@ -196,7 +196,7 @@ static int __init housekeeping_nohz_full_setup(char *str) >> unsigned long flags; >> >> flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | >> - HK_FLAG_MISC | HK_FLAG_KTHREAD; >> + HK_FLAG_MISC | HK_FLAG_KTHREAD | HK_FLAG_SCHED; >> >> return housekeeping_setup(str, flags); >> } > find_new_ilb() already has HK_FLAG_MISC to prevent an isolated CPU > from being elected as an ilb. So I think we should simply remove HK_FLAG_SCHED. There is a check for HK_TYPE_SCHED in nohz_balance_enter_idle() and nohz_newidle_balance(), though it is essentially a no-op as the cpumask has all the CPUs. If we remove HK_TYPE_SCHED, the question now will be whether we should remove the checks at these 2 functions or change them to HK_TYPE_MISC. Cheers, Longman > > Thanks. >